How to choose a roofer in London

Public liability insurance covers damage a roofer does to your property or somebody else's: a slate through a conservatory, a ladder foot through a window, water in overnight because a tarpaulin let go. It does not cover the quality of the work. That is the guarantee, a separate question with a separate answer.

Ask for the certificate itself — a photograph or a PDF is fine — and check three things. The name on the policy matches the name on the quote and the bank account you would pay. The dates are current, because these run a year at a time and lapse quietly. And the limit suits the job: most domestic roofers carry £1m, £2m or £5m, £2m is common on houses, and £5m is what many managing agents and councils insist on.

If the roofer has employees on your roof, employers' liability is a legal requirement and the minimum cover is £5m. A genuinely self-employed one-man operation does not need it. Either way, a certificate takes thirty seconds to send. We send ours before we start, and so will most decent firms. A trade that goes quiet when asked has told you something.

A quote is a fixed price for a described piece of work. An estimate is an informed guess that can move. Both are legitimate, and the trouble starts when the roofer means one and the customer hears the other. Ask, in those words, which you have been given, and get the answer in writing.

If it is an estimate, ask what would push it up and by roughly how much. A straight answer to that is the most reliable signal you will get about how the rest of the job goes.

A single total on a compliment slip is neither. It is a number. A usable quote names the property, the slopes, the materials, the access and what happens to the waste. Two quotes a long way apart are usually two different pieces of work rather than two different rates, and you cannot see that until the scope is on paper.

This is the clause that decides how close the final invoice lands to the quote. Most quotes do not have it.

A roof keeps its real condition under the covering, and there are three finds that come up again and again. On a Victorian slate roof, fixings that have all reached the end together, so the slope is dropping sound slate. On a tiled roof, batten ends rotted where a valley or a chimney has leaked quietly for years. On a flat roof, a deck that has gone soft, which nobody can find by standing on it.

So ask two questions. What allowance is already in the price — so many metres of batten, a rafter end or two, a few square metres of deck. And what happens past it. The answer you want is that the job stops, the roofer photographs it, rings you and prices it before anything further is cut. The answer to be wary of is 'extras at day rate', or nothing at all, because then the agreed number was only ever a starting point.

A genuine find has a size you can check against; an invented one usually does not.

The average is the least useful number on the page. A perfect ten from six reviews posted in one fortnight tells you less than a nine-and-a-half from fifty spread over three years, because the second has survived some winters.

Read the middling reviews, and read the replies. A trade that answers a three-star review with something specific will pick up the phone when something goes wrong on your roof. One that answers nothing has shown you how the difficult conversation goes.

Platforms check different things. Checkatrade runs a set of vetting checks before a member is listed and ties reviews to jobs the trade submits: the vetting is real, the sample is chosen by the trader. Google is open to anyone with an account — wider sample, less checking. Together they are quite a good picture. Ours are 9.45 out of 10 from 53 Checkatrade reviews and 5.0 from 20 on Google, both linked from this site.

The strongest evidence is not on a website. Ask for two addresses within a mile finished in the last year and go and look from the pavement: a straight ridge line, neat verges, lead dressed rather than creased, flashing let into the mortar joint rather than sat on the brick and sealed with mastic. That last detail is the quickest tell there is.

Roofing is not a licensed trade in this country. Anyone may print cards and start tomorrow, which is why the schemes exist. They are worth understanding rather than counting.

None of those schemes is a licence, and none promises the roof will be right. Membership costs money and administration, so plenty of careful small firms sit outside all of it, and a badge on a website is not a live membership. Every scheme publishes a register, and searching a company name settles it in a minute.

Ours is the straightforward part. Harrington holds no trade accreditations today — no NFRC, no TrustMark, no CompetentRoofer, no manufacturer approval. Our vetted listing is Checkatrade, our insurance certificate is available on request, and because we are not in a self-certification scheme, notifiable roof work goes to your borough's building control rather than being signed off by us. If a scheme-backed guarantee is what you need on a large job, a member firm is a fair choice, and we would rather you made it knowing than found out later.

The script is consistent. Someone was working up the road, has materials left over, and noticed from the street that your ridge is cracked or your slates are slipping. They can take a look now, for nothing.

The mechanism does not hold. Cracked ridge mortar, a lifted flashing apron and nail sickness are invisible from a pavement, let alone a moving van. And leftover materials are worth money — they go back to the merchant or into the yard for the next job, not into a discount for a stranger.

What follows is predictable. Once someone is on your roof unwitnessed, the report gets worse, and the photographs may not be of your roof at all. Something urgent is found, the price climbs mid-job, the pressure is to pay cash today, and the paperwork is a mobile number that later stops answering. Older homeowners living alone are targeted most.

The law helps, and it is worth knowing before it happens. A contract agreed at your doorstep for more than £42 gives you fourteen days to cancel, and the trader must give written notice of that right. If they did not, the cancellation window can run for up to a year. To start work inside the fourteen days you must ask in writing, and you can be charged for what has genuinely been done.

In practice: do not let them up. Take a name and a number, say you will ring, close the door, then get quotes on your own timetable from people you found yourself. Report doorstep trading to Trading Standards through the Citizens Advice consumer helpline, and ring 999 if you feel pressured in your own home. Not every knock is a fraud — a scaffolder next door may have seen something real — so check them exactly as you would anybody else.

And nothing on a roof has to start this afternoon. Even an active leak is contained first and priced afterwards. Urgency is the tool; slowing down costs you almost nothing.

None is proof on its own. Two or three together, and it is worth ringing somebody else.